Throughout this application various publications are referenced, many in parenthesis. Full citations for each of these publications are provided at the end of the Detailed Description. The disclosures of each of these publications in their entireties are hereby incorporated by reference in this application.
Transfusion therapy worldwide relies on the availability of fresh and viable red blood cells (also known as erythrocytes). Red blood cells from various donor sources can be packaged and stored for future use in transfusion therapy. The shelf life and viability of the stored red blood cells has a great impact on how many of these packaged cells are wasted, since non-viable or expired red blood cells must be discarded.
As early as 1947, attempts to prolong the shelf life of packaged red blood cells have been made. These attempts began with the use of the nutrient-anticoagulant solution acid-citrate-dextrose (ACD) for the preservation of whole blood (Gibson et al. 1947; Ross et al. 1947). Gibson et al. (1957) later reported that blood stored in citrate-phosphate-dextrose (CPD) was more stable than blood stored in ACD. Storage at 4.degree. C. and the addition of 0.25 mM adenine further increased the viability and storage time of red blood cells (Valeri and Zaroulis 1972; Kreuger et al. 1975). Addition of citrate-phosphate-dextrose-adenine solution, with additional added glucose (CPDA-1), thus became the preferred method for increasing the storage time of red blood cells.
Attempts at further improvements in the storage time of red blood cells began to focus on lipid peroxidation (Hochstein and Jain 1981). Lipid peroxidation is the oxidative deterioration of polyunsaturated fatty acids in cell membranes, and is a widely accepted mechanism for cellular injury and death (Gutteridge and Quinlan 1983; Halliwell 1984; Halliwell and Gutteridge 1984).
Lee (1980) reported that the addition of reduced glutathione (GSH), a naturally occurring antioxidant, and ethylenediaminetetraacetic acid (EDTA), an effective metal chelating agent, significantly reduced lipid peroxidation in plasma stored at 4.degree. C. to 5.degree. C. The addition of both agents resulted in additive reduction in lipid peroxidation. Knight et al. reported that the addition of various metal binding chelators to both irradiated (Knight et al. 1992a) and non-irradiated (Knight et al. 1992b; Knight et al. 1992c) blood resulted in significantly reduced lipid peroxidation levels. Oral supplementation with vitamin C and E, well-accepted free radical scavengers, also resulted in decreased lipid peroxidation in both irradiated and non-irradiated red blood cells (Knight et al. 1993).
Knight and Searles also tested the effects of a variety of other antioxidants on lipid peroxidation in stored blood in an attempt to define other possible agents that might improve red cell life-span of transfused blood (Knight and Searles 1994). These other antioxidants included the metal chelator phytic acid, the transition metal ions zinc (II) and manganese (II), and the free radical scavengers quercetin, N-acetylcysteine, mannitol, uric acid, and 1,3-dimethyluric acid. In this study, Knight and Searles used a 1.0 mM preparation of N-acetylcysteine (NAC) and concluded that NAC was mildly effective at reducing lipid peroxidation in stored whole blood after 7 and 14 days, but was not significantly different from controls on day 18. In view of these results and the results with the other antioxidants tested, Knight and Searles concluded that all of the antioxidants studied, except phytic acid and possibly urate and NAC, might be useful either alone or in combination with other selected agents in increasing red cell life-span and extending allowable storage time prior to transfusion.
In view of the massive amounts of packaged red blood cells used in transfusion therapy today worldwide, a need continues to exist for additional and better ways to prolong the shelf life and viability of the stored red blood cells. Increased shelf life and prolonged viability has a great impact on how many of these packaged cells are wasted, since non-viable or expired red blood cells must be discarded.